Ultrastructural localization of carbonic anhydrase in lysosomes.

Ultrastructural localization of carbonic anhydrase was determined by applying Hansson's histochemical method to glutaraldehyde-fixed frozen sections of guinea pig peritoneal polymorphonuclear leukocytes (PMNs) and lysosomes isolated from rat liver tissue after the animal had been injected with Triton WR-1339. A positive histochemical reaction for carbonic anhydrase in PMNs was found in the matrix of lysosomes. After PMNs phagocytized polystyrene latex particles or emulsified paraffin oil droplets, a positive reactivity for carbonic anhydrase was found in the space between the lysosomal membrane and the particle. Liver lysosomes also revealed positive carbonic anhydrase histochemical reactivity. To confirm the histochemical reaction, indirect immunoferritin labeling was conducted with rabbit antibody to human red blood cell carbonic anhydrase C on glutaraldehyde-fixed, freeze-thawed human PMNs. Immunolabeling was observed in lysosomes. These results suggest that carbonic anhydrase is a constituent of lysosomes of PMNs and liver cells.